Fuse for antiaircraft projectiles



June 21, 1932. T. B. DOE

FUSE FOR ANTIAIRCRAFT PROJEC'IILES Filed June 6, 1930 2 Sheets-Sheet l'Pagan im 21,1932 i Lemie nnen sfrar s PATENT orriec THOMAS B. DOE,` FNEW YORK, N. Y. l

FUSE `lOIIt ANTIARCRFT POJECTILES Application filed June 6, 1930. SerialNo. 459,556.

lThis invention relates to fuses for proj ec-` ploded prematurely.' Afurther object of tlie tiles, particularly to the type of projectileinvention is to so construct the fuse cap that which is detonated at apredetermined point it may be manufactured entirely separately in itsflight. Such projectiles are largely from the detonator and otherexplosive p j employed in antiaircraft gun fire. Usually charges sothatthe fuse may be inanufac- 55 such fuses are operated on the timeprinciple, j tured in any machine shop without danger of the `projectilebeing detonated `at a predeexplosion. j termined time after it is fired.By my in-` Referring to the drawings showing several iveiition, on theother hand, I propose to repreferred forms of the invention,

l place the costly and delicate timing mecha- Fig. l shows a frontelevation of my fuse o0 nisin no w employed by a simple device which Capready to be applied to the main shell. depends primarily on the velocityof the pro- Fig. 2 is a vertical section of the same. jectile andisoperated by the pressure of the Fig. 3 is a detail of the hammer whichair on the nose thereof which, of course, is a explodes the detonator.

function of the velocity. Since the velocity i Fig. 4 is a verticalsection taken at right 65 of the projectile at any given point in itsangles to Fig. 2. Y j

flight is a function of the distance of the pro- Fig. 5 is a sideelevation of the lowerlporjectile from the gun, it is obvious that thetion of the fuse. i

y air pressure at its forward end at any given Fig. 6 is a verticalsection showing a modipoint is also a function of the distance from fiedform of fuse. j 7o the gun. o It is, of course, necessary to take Fig.(il-A is an enlarged sectional detail j into account the height of theprojectile, atof a portion of the mechanism in Fig. 6 but mosphericconditions, etc., but such factors with the parts shown in a slightlydifferent may all be taken Vinto account in the setting position. v

` of the fuses. The air pressure on the nose of Fig. 7 is an enlargedSectional detail of a 75 the `projectile may be balanced against anyportion of this mechanism,

settable yielding means within the projectile7 Fig. 8 is an enlargedview of the middle such as spring' pressure or the like. I preferportion of Fig, 6, the parte boing Shown in n to makeuse of the rotationof the projectile different Position,

on its own axis (which is imparted bythe Fig. 9 is a vertical section ofa slightly' S0 riiiing in the gun) to create the yielding force modifiedform of my invention ora pOlOIl thereof WhlCll OlpOSQS lll@ 211 Fig. l0is a vertical section of a form of pressure, by employing free orpartially free the invention using a spring means or a conimasses withinthe projectile on Which the bination of Spring and Centrifugal moans asCentrifugal foyoo acts, I provide a. .simple the withdrawing forceV forthe detent. 85

` and reliable means within the projectile for Fig 11 is a horizontalSection on 1in@ 11- 11 opposing the air pressure means since the ofFig10,

speed of rotation of the projectile is nearly In the Sectional gnros a,firing pin or a constant quantity, th@ TOUOH defeaslng hammer 1 is shownas slidably mounted in lll VelOClt'y Very Slowly @ncl at a lmOWll l'a'eatransverse bore 2, the hammer being noi- 9o This Celllllfllgal fore@Wlll Olelclle lll@ inally locked in its mid-position in the bore.

OICG Created by lll@ all' P leSS'lle 011 f1 P01" Said bore preferablyextends entirely OD ofthe T1055@ 0l lll@ PlOleClll@ al? Ll Pledfe*through the main body 3 of the nose cap, the lemlled Pollll lll thelllllt 0l lll@ Pl'olecllle Vouter ends of the bore being threaded. Intoand iS llgd, when that OCCU'S t0 lllP these ends one or more detonatorcaps l and 95 a Cletcllt and l'lS@ the 'lllllllfll i 4 may be screwedafter the fuse is completely Other ObjeCtS 0f the llVGIl'lOIl 3T@ t0 111manufactured and ready to be placed on the PI'OVG HP0 fuses 0l the abovetype by Slllplshell. Said caps communicate with powderfying the same andrendering them absolutetrain channels 5 which lead downwardly ly foolproof `so that the fuse can not be exthrough space 6 and channels 7 intothe main 100 Vwhich direction it moves, I provide a be purposelyweighted on one side or the` Y other or purposely placed out of thecen-v ter line of the AVshell, since in the ordinary course ofmanufacture the center of gravity of the same will always be enough outof line with the center of gyration of the shell to l` actua-te thehammer in one direction orthe otherupon its release. In orderethat thehammer may explode the'shellregardless in detonator at each end of thechannel. f

This also has the advantage thatthe shell'` may be balanced about itslongitudinal axis prior Vto the insertion of the firing pin and thisbalance will not be materially disturbed by the addition ofthe firingVpin since it need f not be purposely made heavier on oneside in order toinsure firing asexplained above.

For normally lockingy the hammer inV place I provide a detent 8 whichengages `ln a annular channel in the periphery of the hammer. The hammeras shown in Fig.'v 3 is provided with a passage 10 therethrough so thatan air cushion will not be formed as the hammer moves toward one of thedetonators. For the same purpose, apertures 0,0 may be provided throughthe shell for by-pa`ssing the air around the hammer. The detent ispreferably arranged to be Withdrawn when'the air pressure at the nose ofthe projectile falls below a predetermined amount. Y

In order to provide the withdrawing force I also prefer to make vuse. ofthe rotation of' the shell, the centrifugal force acting on adjustablemasses within the nshellto overcome the air pressure and lift thedetent. In the form shown in Figs. 6 to 8, which represents thepreferred formV of my invention, there is mounted on the stem -8 of thedetent a flat triangular shaped member 11. The centrifui gal massesappear in the side elevation as L- shaped members 12-13. 'Each ofsaidmembers has a flat unitary base 14 which extends under the member 11.'Ihe upstanding portion of each member, however, isV forked to formtwoAears 12 and 12, which extend to Y each side of the member 11 (seerFig.7).

Each centrifugal member is mounted on a base .or plate 16 being normallyheld in placeV by the pin 17 extending upwardly from the plate andVfitting loosely in a hole into the base 14. Each plate 16 is'slidablymounted on a slotted member 18 and may be adjusted toward and away fromthe center of the shell by means ofV a nut 19 threaded on the screw 20.Each nut has a pin 21 extending upwardly therefrom through the slot 22of member 18Qand which Vextends into a. hole in the plate 16 so that asthe Vscrew is turned the plate will be moved toward and away from thecenter other hand, the corresponding members are` shown as separatedsomewhat.

Under the action of centrifugal force acting on theupright forked ears12-12, each member l2-13 will be rotated about its tip end 23r of thebase 14 which is shown Las resting in an angle formed by lug 24 at theend of the plate 16 (see Fig. 8). As each memberY rotates about thispoint it will obviously raise thetriangular member 11 as shown inexaggerated form in Fig. 8, thus withdrawing the detent 8 from theannular .groove in the hammer. It should be noted that the point 23aboutfwhich each centrifugal member rotates lies in substantiallythesame'horizontal plane Y Y as the inner edge 25V of the base 14, or inother words, the line of contact between the base 14 and member 11 as ittilts upwardly. Thisl Yis for the purpose of securing the free disengagement of base 14 from pin 17 and maxi# mum lifting effect on themember 11 at the start of the outward movementof the centrifugal members12, 18, .since once the lifting is started it will be continued by therapid building up of the centrifugal forces due to the outward movementof the tops of the parts 12 and 13. To the same end the base may belongitudinally grooved to lower the member 11 and also hold it in place.In order to maintain this relationship between the toe 23 and the crotch25, the member 18 is preferably positionedV with its upper surface on laslant as shown. rIhe screw 2O likewise may be shown slanted upwardlyalthough this is not necessary Vas shown in Fig. 9. The adjustment ofthe screws is simultaneously effected by means "of the range settingring 26 which extends around the nose cap and is interiorly providedwith` teeth 27 meshing with pinions 28-29 on theends respectively of thescrews 2020. The 'graduations are read on a reference mark or marks M ona fixed ring 26. The ready 'manner in which the parts maybe assembledand disassembled isY shown in Fig. 5. By unscrewing nose piece 50 andintermediate member`51, the graduated ring 26 and the reference ring 26may be slipped` off, thus exposing the cross apertures 52, in which areplaced the members 18 containing screws 20-20..

While there is no force acting to release the detent until the shell isrotating at high velocity, I prefer to provide an additional safetylocking means which I have shown as in the form of fiat springs 30 whichare pinned to the interior of the shell and normally lie in grooves 31in the member 11. said springs lie in said grooves it is obvious thatmember 11, and hence detent 8,'cannot be As long as moved upwardly.AWhen, however, the shell j is rapidly rotated, the ends of fiat spring30, under the action of centrifugal force, move outwardly out of thenotches lock the member 11. At `its upper end the stem 8 is providedwith a piston-like member 32 shownas threadedon the stem and fittingclosely into a bore in the body portion of the nose cap. The top of saidpistonis subject to the air pressure,

31 so'as to unj the nose beingprovidedwith an axial bore with a space 38under the piston. As the projectile rushes through the air, air will'bedrawn from the channels 36-37 to create a negative pressure in the space38 and thus augment the positive pressure on the upper surface of thepiston for the purpose specified.

Owing to the fact that during the interval that the shell is beingexpelled from the gun the air pressure on the nose may not be built up,I prefer to provide an additional safety device for preventing explosionduring this interval. This preferably takes the form of a metal ball orequivalent free object which normally lies at the lowest point in the U-shaped channel 34 and has a close but free fit in said channel. It isobvious that when the ball is in the position shown, i. e., with theshell sitting upright on its base that the detent cannot be raised.During the time that the shell is leaving the gun there is enormousacceleration of the shell and the inertia of the ball holds it in itscenter position in spite of the building up of a high velocity ofrotation. This acceleration of the shell continues some distance beyondthe muzzle as has been shownexperimentally so that explosion of theshellwithin the gun orvery close thereto is affectively prevented.

. The form of the invention shown in Figs. 2 and 4l operates on asimilar principle to that shown in Figs. 6 and 8. In this form thecentrifugal members 12-13 are shown as triangular in shape and rest attheir base as before in notched members 41 which are threaded on screws4:2*l2-l The tops of said members rest against the under-surface of thepart 11 secured to the stem 8. Under the action of centrifugal force thetops of the triangular members will be thrown outwardly7 rotating themembers about their toes 23 and thus lifting the member 11 and thedetent.

j In order `to maintain the proper relationship between the point oflift and the pivotal point of the centrifugal masses 12 and 13, it

vis not necessary to have the screws 20 and i 20 in an inclinedposition. Fig. 9 shows a construction in which the corresponding screws`90--90 are placed horizontally and the aforesaid proper relationshipmaintained by making the slide-ways 22', on which the pieces 16 slide7of triangular shape so that the top surfacethereof presents an inclinedsurface.` Fig. 9 also illustrates a modified form of locking spring. Inthis form two springs 91 and 91 are secured adjacent their tops to aAfixed part of the shell with their free ends projecting downwardly toengage a flattened portion 92 on the member 11. The springs may beweighted near their lower ends so that under the action of centrifugalforceV the lower ends will fly outwardly and release the `member 11.Otherwise the action of this form ofthe invention is the same as Fig. 8.

Instead of employing centrifuga-ily operated means as a yielding forceto release the detent, I may employ a spring means either with orwithout centrifugal action. One form of such means is shown in Figs. 1Uand 11. In this form of the invention the hainmer 69 is normallymaintained `locked in the retracted position by one or more detents orlocking pins. One of said pins 70 is a safety catch which prevents al'lpossibility of the shell being exploded prematurely. Said detent is on amass 71 normally held in place by the split ring 72 which lies partlywithin a recess 7 3 in a nut 74 and partly in an annular recess in themass 71. When the projectile is discharged from the gun, however, theinertia of said mass 71 is sufficiently great to snap it to the bottomof the bore 75 where it is held by the closure of the ring over the topthereof. The projectile is thus armed andrea-dy to fire upon the releaseof the main detent or pin 76 from engagement with hammer 69.

Said pin projects downwardly from a stem 77 having a plurality ofshoulders and threaded portions thereon. Said stem at its top is flaredat 78 to form the nose of the projectile and may also be provided with aslot 7 9 for rotation by a fuse setter. The stein first passes throughaA locking ring 80 threaded in the projectile which holds in place arotatably munted nut or sleeve 81. Said ring is threaded interiorly,preferably with a lefthanded thread, and engages corresponding threads82 on the stem. Sj'iring-presser locking balls 83 (see Fig. 11) areplaced in transverse bores in the shell and engage the exterior of saidring 81. Said balls serve to lock the sleeve 81 against rotation in onedirection, i. e., clockwise rotation in Fig. 11, but permit the sleeveto be rotated in the epposite direction.

Secured adjacent the bottom of said stein is a flat coil spring 841-.Said spring is preferably anchored at one end to the stem and at theother end to a pin 85. The spring is normally under more or lesstension, i. e., is wound up so that it tends to rotate the steinpredetermined range extent.

in a clockwise directionV in Fig.l 11. By turning the stem by means of ascrewdriver or fuse setter in a counter-clockwise direction in Fig. 11,the spring will be Wound up for a During such operation, however, theVnut freely rotates with the stem, so that no axial adjustment of thestem takes place.

I also prefer to provide an auxiliary safety device for preventing thespring from prematurely unwinding and releasing the hammer. This deviceis preferably in the form of a pair of masses 86, each having aprojection 87 thereon which engages a collar 88 threaded on stem 77 andhaving an annular shoulder 89. Said masses are normally pressed intoengagement with said collar about said shoulder by springs 9() whichpress at their outer ends against threaded closures 101. As shown, Iprefer to place each of said masses in a bore which extends transverselybut at an angle to i a transverse plane passing through the projectile.The centrifugal force tendsto withdraw the masses as soon as the normalspeed of `rotation is approached,but due to the forward inclination ofthe bores in which'they are placed, the centrifugal force is opposed bythe inertia of the masses while the projectile is receiving its powerfulaccelerating impulse from the powder. Therefore, the masses will not bedisengaged rfrom the locking collar until the shell is well beyond themuzzle of the gun as in the other forms of the invention. Y 1 Y Thisformv of the invention is set for range as follows: The parts areassembled in the position shown in Fig. 10, with the detent-76 engagingthe hammer 69 and the spring under no or slight tension. The device isthen set for range by turning the nose cap. The centrifugal masses 86donot prevent this since no axialmovement of the pin takes place and thenut 81 has a smooth periphery. This adjustment is effected by turningthe stem counter-clockwise or to the left in Fig. 11 so that the nutrotates with the stem and no axial movement takes place. VAfter theshell is fired, however, and the locking pins are all released, thespring will unwind the stem 77 and screw it outwardly thro-ugh the nut81(which is locked in place against clockwise rotation) as soon as the airpressure on the nose falls below a predetermined amount.

The accuracy of my fuse depends, of course, somewhat on maintaining themuzzle velocity substantially constant. If the muzzle velocity isgreater than anticipated, the fuse may be set off prematurely with thecentrifugal method, as shown in Figs. 1 to 9 because the velocity ofrotation of the shell will be more than correspondingly increased; whileif the i muzzle velocity and, therefore, the speed of rotation, is lessthan anticipated, the fuse will be set off too late. On the other hand,if a spring were employed which was uninfluenced by centrifugal forces,itrwould set 0E the fuse late Vwhere the {muzzleyelocity was greaterthan anticipated, and early if the muz-V zle velocity 'wereV less thananticipated.V If these two methods arecombined, however, the error dueto change in'muzzle velocity may be reduced to a very small amount. Theform n of spring shown in Fig. 10 is subject, to a tion of rotation ofthe shell. `This formof the invention,.therefore, really combines thespring and centrifugal methods and thereby reduces the error referredto. Y

In accordance with the provision of the patent statutes, I have hereindescribed the principle and operation of my invention, to* gether Vwiththe apparatus which I now consider to represent the best embodimentthereof, but I desire to have it understood that the apparatus shownisonly illustrative and thatJ the invention can be carried` out by othermeans. Also, while it is designed to'use the various features andelements in the combination and relations described, some of these maybe altered and others vomitted without interfcringwith' the more generalresults outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure byLetters Patentv 1S: 1 1. In a fuse. for projectiles, the combinationwith the hammer, of a detent for normally holding said hammer retracted,means subject Vto the air pressure dueto` the flight of the projectilefor holding said detent in place, and yielding means opposing said othermeans for withdrawing said detent when the air pressure becomes a`predetermined amount. Y

2.V In a fuse'for projectiles, the combinationwith the hammer, of adetent for nor- Vmally holding said hammer retracted, means subject tothe air pressure due to the flight of the projectile for holding saiddetent in place, yielding means opposing said other means forwithdrawingsaid detent when the air pressure becomes a predeterminedamount, a lock for Vpreventing said yielding means from acting beforethe'projectile has beenA discharged, said loclr being subject tocentrifugal force so as to. unlock said means after the projectile isfired.` Y Y 3'. In a fuse for projectiles,-the combination with thefiring cap and hammer, of a detent for normally holding said hammerretracted, a movable vmember in the nose of said projectileand/connected to said detent for holding it in place, and settableyielding means for withdrawingfsaid detent when the `pressure on thenose falls below a predei tent, the release -of said locking means, in

turn, being opposed by acceleration forces whilethe projectile isleaving the gun.

.l 5. In a fuse forprojectiles, the combination with the hammer, of aldetent for normally holding said hammerretracted, means subject to theair pressure Jdue to the flight of the `projectile for holding said,detent in place, movable masses within the projectile subject to thecentrifugal force created by the rotation thereof for withdrawing saiddetent when the air pressure becomes al predetermined` amount,` andsettable means for varying the effective force exerted by `said masseson said detent for varying the range at which the shell explodes.

. 6. Ina fuse for projectiles, the combination `with the hammer, of adetent for normally holding said hammer retracted, yielding meanstending to withdraw said detent comprising a pair of centrifugal memberspivoted on opposite sides of said detent and adapted under the action ofcentrifugal forces, due to rotation of the projectile, torotate'outwardly and lift said detent, means for adjusting said massestoward and away from the axis of the projectile to vary the range, andmeans responsive to air pressure of opposing said withdrawingr force.

7 In a fuse for projectiles, the combination with the hammer, of adetent for normally holding said hammer retracted, yielding meanstending to withdraw said detent comprising a pair of centrifugal memberspivoted on opposite sides of said detent and `adapted under the actionof centrifugal forces, due to rotation of the projectile, to

.rotate outwardly and lift said detent, and

means responsive to air pressure for opposing said withdrawing force.

8. ln a fuse for projectiles, the combination with the hammer, of adetent for normally holding said hammer retracted, cen- `trifugallyoperated means for withdrawing said detent comprising a member mounted fto one side of the axis of the projectile to pivot about the outer edgeof its base under the action of centrifugal force and to raise saiddetent when so rotated, settable means for varying the distance of saidmember from the axis of said projectile to vary the range,

a and means for exerting an opposing force to the centrifugal action ofsaid member on said detent.

9. In a fuse for projectiles, the combination with the hammer, of adetent for normally holding said hammer retracted, means subject to theair pressure due to the flight of the projectile for holding said detentin place, movable masses within the projectile subject to thecentrifugal force created by the rotation thereof for withdrawing saiddetent when the air pressure becomes a predetermined amount, settablemeans for varying the eli'ective force exerted bynsaid masses on saiddetent for varying the range at which the shell explodes, and inertiaoperated safety locking means for preventing withdrawal of said detentuntil the projectile has left the gun.

10. In a fuse for projectiles, the combination with the hammer, of adetent for normally holding said hammer retracted, means subject to theair pressure due to the flight of the projectile for holding said detentin place, and combined spring and centrifugal means for withdrawing saiddetent when the air pressure falls below a predetermined amount.

11. In a fuse for projectiles, the combination with the liring cap andhammer, of a detent' for normally holding said hammer retracted,avmovable nose on said projectile connected to said detent for holdingit in place, and `settable spring means also subject to centrifugalforces for withdrawing said detent when the pressure on the nose fallsbelow a predetermined amount.

12. In a fuse for shells,\the combination with the firing pin andlocking detent, of centrifugally operated mea-ns for withdrawing saiddetentcomprising an L-shaped member adapted to pivot about its outeredge under the action of centrifugal force on its top, said` pivotingedge being substantially on a line with the point of lift of said memberon said detent. V

13.1n an air pressure fuse for projectiles, a detent for locking thefiring pin, centrifugal means for` withdrawing said detent, acentrifugally released spring lock for preventingaccidental withdrawalof said detent, and

an additionalmeans for preventing explosion- 15. ln an air pressure.fuse for projectiles, a detent for locking the firing pin, centrifugalmeans for withdrawing said detent, a centrifugally released spring lockfor preventing accidental withdrawal of said detent, and means forpreventing explosion in the gun barrel comprising a ball in a U-shapedchannel disposed across the axis of the shell above said detent andadapted to prevent withdrawal of said detent while it lies near thebottom of said channel.

16. A fuse .for projectiles, in combination with a nose cap, of a crosschannel therethrough, a substantially symmetrical Yfiring pin normallyheld therein at about the longitudinal axisof the projectile, and apercussion'cap holder adapted to be detachably secured in each end ofsaid cross channel whereby the shell is not materially unbalanced aboutits longitudinal axis by said firing pin.

17. A fuse for projectiles, in Combination with a hammer, of a detentfor normally holding said hammer retracted, a piston member connected tosaid detent for holding the same in place, the upper surface of saidpiston being subject to the air pressure at the nose' of the projectile,and rearwardly inclinedl channelsin said projectile leading to theunder-surface of said piston whereby a negative pressure is createdthereon, and yielding means for opposing said piston for firing theprojectile when the effective pressurev on the piston falls below apredetermined amount.

18. In a fuse for projectiles, the combination with the Vfiring pin andlocking detent, of means for withdrawing said detent, at a predeterminedpoint in the flight of the shell, and a safety lock forpreventingpremature release in the gun barrel comprising a U- Y shapedchannel extending across the axis of the shell and above said detent,and aball in said channel whereby inertia holds the ball over the detentduring acceleration of the shell but centrifugal force displaces it asacceleration ceases.

19. In an air pressure fuse for projectiles,

a detent for locking the firing pin, centrifugal means for withdrawingsaid detent, and means for preventing explosion in the gun barrelcomprising a ball in aY U-shaped channel disposed across the axis of theshell above said detent and adaptedvto prevent with'-V drawal of saiddetentY while it lies near the bottom of said channel whereby. inertiaholds f an inertia lock subject both to opposed transprevents lifting ofsaid detent as long as the ball remains in the cup. l j l 22.111 asafety fuse for projectiles, the combination with the firing pin andlocking detent, of means for preventing premature release of the detentincluding a cup on the detent, and a ball in said cup and normally heldtherein by gravity with the shell sitting on its base and by inertiaduring the acceleration of the shell in the gun barrel but expelledtherefrom by centrifugal force as ac-` celeration ceases.

In testimony whereof I have aflixed my signature.

